alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE HTA.BabyShark Checkin"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/expres.php?op="; fast_pattern; pcre:"/^\d/R"; http.user_agent; content:"Mozilla/4.0 (compatible|3b 20|Win32|3b 20|WinHttp.WinHttpRequest.5)"; http.referer; content:".hta"; reference:md5,94b60cf91e550e1d981aaf9962d52e18; classtype:command-and-control; sid:2027365; rev:3; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2019_05_20, deployment Perimeter, malware_family BabyShark, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2020_08_28;)